1. Technical Field
The present disclosure relates to an expandable seal arrangement, and associated method, for sealing a gasket to an annular wall of a rigid structure.
2. Description of the Related Art
Manhole access ports are often assemblies of various components placed adjacent one another, and have joints which may also need to be sealed from leakage. For example, it may be desirable to provide a seal across a manhole frame, optionally one or more grade rings, and a manhole chimney to prevent moisture infiltration into the fluid passageway accessed by the manhole access port.
In underground pipe systems, it is often necessary to connect a pipe in a sealed manner within an opening in the wall of a rigid structure, such as a manhole riser or monolithic base, for example. Typically, a flexible elastomeric gasket is placed within the opening in the wall, followed by fitting an expansion ring against the interior surface of the gasket. Thereafter, a suitable expansion mechanism is used to radially expand the expansion ring and lock same in an expanded condition in which the gasket is sealingly compressed between the expansion ring and the opening in the wall of the structure. Thereafter, a pipe is inserted through the gasket, and one or more clamps are installed around a portion of the gasket which extends from the wall to sealingly compress the extending portion of the gasket between the clamps and the outer surface of the pipe. In this manner, a sealed connection is made between the pipe and the structure.
Similarly, sealed connections between two pipes are frequently made. Underground pipes which are used in municipal water and sewer systems, for example, typically include bell and spigot ends that are attached to one another in a sealed manner. Typically, either the spigot end or the bell end of such pipes includes a rubber seal which is compressed between the ends of the pipes to provide a sealed joint when the spigot end of one pipe is inserted into the bell end of another pipe. Occasionally, these primary joint seals between adjacent pipes may leak after installation in the field, requiring a secondary sealing assembly to seal the connection.
Yet another application for a pipe seal is the fixing of a leak within a pipe structure. Where a pipe has begun allowing ingress of moisture, such as through a hole or crack in the wall of the pipe, a gasket may be placed within the wall of the pipe spanning the structure, and each side of the gasket may be sealed to prevent further leakage into the pipe.
To make the above seals, a flexible elastomeric gasket may be placed against the pipe or manhole wall, followed by fitting an expansion ring against the interior surface of the gasket. Thereafter, a suitable expansion mechanism is used to radially expand the expansion ring and lock same in an expanded condition so that the gasket is sealingly compressed between the expansion ring and the wall of the pipe or manhole at the joint. Thereafter, a pipe is inserted through the gasket, and one or more clamps are installed around a portion of the gasket which extends from the wall to sealingly compress the extending portion of the gasket between the clamps and the outer surface of the pipe. In this manner, a sealed connection is made between the pipe and the structure.
What is needed is an improved expansion ring mechanism and sealing assembly for sealing joints in fluid-carrying structures such as manhole access ports, underground pipes, and underground pipe junction points, for example.